While you’re out buying the charcoal briquets for your Memorial Day barbecue this year, you’ll probably want to pick up some sunscreen, too. But, of the dozens of varieties that appear on store shelves, which is the best one to buy?

Just in time to help you choose, the Environmental Working Group (EWG) has released its fifth annual guide to sunscreen products — including lip balms and sunscreen-containing cosmetics — rating them for both safety (based on whether they contain toxic chemicals) and effectiveness (based on data on how well they block UVA and UVB rays and withstand exposure to the sun).

Since the Food and Drug Administration doesn’t regulate sunscreen, the EWG says, it’s up to the consumer to suss out what’s safe. Incidentally, the environmental group says, 60% of sunscreens on the American market wouldn’t pass Europe’s more stringent regulations.

A couple of general tips: avoid sunscreen sprays, pumps and powders because the chemicals in them can be inhaled, and choose products that use the minerals zinc or titanium as their active ingredient because they’re the most stable. A few other key sunscreen-buying rules from the EWG, below:

1. Check the UVA protection. Protection against both UVA and UVB rays is important. UVA rays account for 95% of the solar radiation that reaches the Earth’s surface and, while they’re less intense than UVB rays, are 30% to 50% more prevalent, according to the Skin Cancer Foundation. UVA is also known as the “tanning” ray and penetrates more deeply into the skin, contributing to aging as well as the cellular damage that triggers skin cancer.

The EWG found that 60% of the 500 sunscreens of SPF 30 or higher it reviewed didn’t have adequate UVA protection. But the problem for the consumer is that most products on the shelf don’t explicitly say how well they protect against UVA; rather they use vague terms like “multispectrum” or “broad spectrum” protection.

The EWG finds that only 1 of 5 sunscreens on the market are both safe and effective; you can check the group’s guide for recommendations before you buy.

2. Avoid oxybenzone and retinyl palmitate. Many effective products contain one or both compounds — oxybenzone and retinyl palmitate — that the EWG specifically suggests avoiding. Oxybenzone is an endocrine disrupter, the EWG says, and retinyl palmitate is a form of topical vitamin A that some animal studies suggest may be linked to an increased risk of skin cancer.

3. Stick with SPF 30. Although sunscreens with high SPFs — of 50 or higher — are growing in popularity, the EWG says they are no more effective than SPF 30 products. And some research suggests that the inflated numbers may actually do harm by giving beach-goers a false sense of confidence and causing them to reapply less frequently or stay in the sun for longer periods.

Of the 1,700 products the EWG reviewed, the group gave top scores to 128; all recommended products contain zinc or titanium and none contain the compounds oxybenzone and retinyl palmitate. There are too many EWG-approved products to list here, so check out the full guide at your leisure.

Reliably, the EWG’s report has met with criticism from the sunscreen industry. Farah Ahmed, chair of the Sunscreen Task Force for the industry group Personal Care Products Council, spoke with WebMD reporter Kathleen Doheny, calling the report “reckless.” Ahmed took issue with the EWG’s rating methodology and noted that there isn’t enough scientific evidence to support the group’s concerns about retinyl palmitate.

However, Doheny reports, Ahmed gave the thumbs up to another “best of” sunscreen ranking, which was released Tuesday by Consumer Reports (CR) Health, in part because the CR testers used real-world conditions (applying sunscreen on volunteers’ backs and submerging them in water for 80 minutes) to gauge stability and effectiveness. By contrast, the EWG rated products based on the “absorbance spectrum” of active ingredients and existing data on their stability.

Of 22 sprays, creams and lotions tested by an independent lab, CR designated three as “best buys:”

Because the CR ratings [with a subscription] take into account only effectiveness and not the potential health effects of individual ingredients, the results tend to contradict those of the EWG. FromConsumer Reports Health:

Almost every tested sunscreen contains some ingredients associated with adverse health effects in animal studies. Oxybenzone and other endocrine disruptors may interfere with hormones in the body, and nanoscale zinc and titanium oxides are linked to problems such as potential reproductive and developmental effects.

Retinyl palmitate (look for it among inactive ingredients), a type of topical vitamin A, is an antioxidant that animal studies have linked to an increased risk of skin cancers. In skin, it converts readily to retinoids, associated with a risk of birth defects in people using acne medications containing them. As a precaution, pregnant women may want to avoid sunscreens with retinyl palmitate.

More research is needed, but as of now, the proven benefits of sunscreen outweigh any potential risks.

One thing on which all reviewers and critics agree is that sunscreen alone is not enough to protect you from sun damage. Consumer Reports Health advises people to wear protective clothing and limit time in the sun; use water-resistant sunscreen, with an SPF of at least 30 (higher SPFs don’t improve protection); reapply sunscreen every two hours or so and always after swimming or sweating; use sunscreen liberally and evenly. And, finally, don’t get suckered by expensive products: CR found that La Roche-Posay SPF 40, which costs $18.82 per ounce, scored lower overall than No-Ad SPF 45, which costs 59 cents per ounce.